Touch screens may be implemented in a device by overlaying a touch-sensitive pad (typically of a capacitive type) over a surface of a display screen. The display screen displays information to a user, and the touch-sensitive pad receives input by detecting the user touching the touch-sensitive pad. Capacitive touch-sensitive pads generally comprise sensors that detect a user's touch by sensing a capacitance between the user's finger and one or more of the touch sensors. The touch (i.e., capacitance) detected by the touch-sensitive pad is received as a user input that is interpreted by the device in accordance with several variables and/or conditions relating to the user's touch. Some of these variables and conditions may include the content displayed on the screen, the status of the device, the location of the touch, the duration of the touch, and combinations thereof. In order to determine some of these variables and conditions, some touch screens implement features that detect a particular type of user touch. One such example is a slide feature that is used to detect a continuous user touch moving across the surface of the touch screen.
One way to implement a slide feature in a touch screen is to designate a particular area over the display portion of the touch screen as a location for sensing the slide touch. However, this obstructs the user's view of the display screen or reduces the effective area for displaying content on the screen. Another solution for implementing a slide feature is to increase the surface area of the touch-sensitive pad to extend beyond the display area of the touch screen. In this implementation, the slide feature may be implemented using touch sensors located outside the display area of the touch screen. Although this solution does not obstruct the user's view of the display screen, the additional touch sensors require additional I/O lines for interfacing the additional touch sensors, which significantly increases the circuitry required to detect and process a user touch.